Luminance and brilliance are attributes of metal effect varnishes. The "Flip-Flop" or two-tone effect is of particular significance.
This effect occurs due to a change in luminance perception during modification of the viewing angle, and it relies on a metal pigment utilized in the varnish and its adjustment in the varnish film.
The incorporation of certain additives promote the “Flop” effect in metal effect varnishes. The visual appearance of the metal effect varnishes is considerably influenced by the additive utilized, especially its particle diameter. Products on a polymethyl urea resin basis can also be employed.
The existence of the fine polymer particles results in a spatial separation of the single metal pigment palettes in the varnish layer, and to a targeted steering of the “Flop." They exert within the varnish a barrier effect and surround the metal pigments present with a flexible frame structure, so that they are constricted in their flexibility.
Unwanted movement of the particles is prevented and a more uniform brilliance, even with different viewing angles, is attained.
The particle diameter of the additive used largely affects the dependency of the visual image of the metal effect varnishes. The image shown below is a finely ground polymethyl urea resin, measured using the ANALYSETTE 22 in an organic solution with a small volume dispersion unit.
This information has been sourced, reviewed and adapted from materials provided by FRITSCH GMBH - Milling and Sizing.
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